During the manufacturing of a capacitor in an integrated circuit an electrically conducting layer is deposited on a layer structure comprising a silicon substrate upon which a thin thermal oxide is grown and in which layer structure active and passive components are defined in a standard way. On this electrically conducting layer, which forms the lower electrode of the capacitor, an electrically insulating layer is then deposited. According to known techniques the electrically insulating layer is patterned and etched in predetermined regions, on the one hand, for electrical connection to the lower electrode of the capacitor and, on the other hand, for the manufacturing of the capacitor itself. This is performed in a single step. A thin dielectric of silicon oxide or silicon nitride is deposited, patterned and etched except for that over the lower electrode. Subsequently, an upper metal layer is deposited, which is patterned and etched to form the upper electrode of the capacitor and the electrical connection to the lower electrode of the capacitor.
With this technique there is, however, the risk present that contact problems occur at the electrical connection, for example because of bad step coverage for the metal. Therefore the electrical connection must be produced with relatively large cross-sectional area. In order to achieve large capacitance values the capacitor must have a large area or extremely small dielectric thickness. In the first case there is a risk for deformations caused by mechanical stresses and in the second case the capacitor becomes unreliable as there is a risk of breakdown present.
It is known from i.a. U.S. Pat. No. 5,406,447 and U.S. Pat. No. 5,563,762 to use capacitor dielectrics of other materials, such as ferroelectric material, e.g. PZT (PbZr.sub.x Ti.sub.1-x 0.sub.3), which has an extremely high dielectric number. In this case neither the area of the capacitor nor its thickness are critical. However, a completely different manufacturing technique is required because of, among other things, the high crystallization temperature of the capacitor dielectric, interdiffusion between the electrodes and the capacitor dielectric and a large sensitivity to impurities.